1. Field of the Invention
The present invention relates to a liquid crystal display device and related driving method, and more particularly, to a liquid crystal display device and related driving method for performing the LCD driving operation based on the sub-pixel voltages with the same polarity in the capacitors of bright section and dark section of each pixel unit.
2. Description of the Prior Art
Because liquid crystal display (LCD) devices are characterized by thin appearance, low power consumption, and low radiation, LCD devices have been widely applied in various electronic products for panel displaying. In general, the LCD device comprises liquid crystal cells encapsulated between two substrates and a backlight module for providing a light source. The operation of an LCD device is featured by varying voltage drops between opposite sides of the liquid crystal cells for twisting the angles of the liquid crystal molecules of the liquid crystal cells so that the transparency of the liquid crystal cells can be controlled for illustrating images with the aid of the backlight module.
It is well known that each pixel unit of an LCD device can be designed to comprise two sub-pixel units for achieving a wide viewing angle. That is, based on gray level averaging effect of two Gamma curves corresponding to the two sub-pixel units, optimal visual experience can be realized in different viewing angles for having a high-quality wide viewing angle. Please refer to FIG. 1, which is a schematic diagram showing a prior-art LCD device. As shown in FIG. 1, the LCD device 100 comprises a plurality of gate lines 110, a plurality of data lines 120, a plurality of common lines 130, a plurality of pixel units 140, and a source driver 180. Each pixel unit 140 comprises a first switch 141, a second switch 143, a first liquid-crystal capacitor (bright capacitor) 145, and a second liquid-crystal capacitor (dark capacitor) 147. The first switch 141 in conjunction with the first liquid-crystal capacitor 145 forms a sub-pixel unit, and the second switch 143 in conjunction with the second liquid-crystal capacitor 147 forms another sub-pixel unit.
Each first liquid-crystal capacitor 145 is charged via a corresponding data line 120 and the first switch 141 of the same pixel unit 140. Each second liquid-crystal capacitor 147 is charged via a corresponding data line 120, the first switch 141 of different pixel unit 140, and the second switch 143 of the same pixel unit 140. For instance, the first liquid-crystal capacitor C1 of the pixel unit P1 is charged via the data line DL1 and the first switch T1 of the pixel unit P1. The second liquid-crystal capacitor C2 of the pixel unit P1 is charged via the data line DL2, the first switch T3 of the pixel unit P2, and the second switch T2 of the pixel unit P1.
While driving the LCD device 100 based on the column-inversion driving operation, the polarities of data signals corresponding to adjacent data lines are opposite to each other. That is, if the polarity of the data signal SD1 is positive, then the polarity of the data signal SD2 is negative, and vice versa. In other words, if the sub-pixel voltage VB1 corresponding to the first liquid-crystal capacitor C1 is a positive-polarity voltage, then the sub-pixel voltage VD1 corresponding to the second liquid-crystal capacitor C2 is a negative-polarity voltage. However, as the polarities of the sub-pixel voltages corresponding to the first and second liquid-crystal capacitors of each pixel unit are opposite to each other, the sub-pixel voltages with opposite polarities have a significant effect on the angles of the liquid-crystal molecules in the main-slit between the first and second liquid-crystal capacitors, which incurs brightness loss in the main slit. Furthermore, the data signal driving frequency should be increased or even doubled for charging the first liquid-crystal capacitor 145 and the second liquid-crystal capacitor 147 of each pixel unit 140 via different data lines 120, and the power consumption of the source driver 180 is increased accordingly. In view of that, the working temperature of the source driver 180 is increased as a result of the high power consumption, and the lifetime of the source driver 180 is shortened following the increase of the working temperature.